In recent years, vehicles driven by electric power have been used.
This leads to a need for supplying electric power to a vehicle.
For example, electric power is supplied to a parked vehicle from an electric power supply apparatus.
The electric power supply apparatus is capable of supplying electric power to a vehicle in a wireless manner.
For example, such an idea is studied that a vehicle has a wireless type electric power supply secondary coil on a bottom part thereof, and an electric power supply primary coil is provided below the vehicle to supply electric power to the vehicle.
FIGS. 24A and 24B are conceptual diagrams of a wireless power transfer system.
The concept illustrated in FIGS. 24A and 24B has been disclosed in U.S. Pat. No. 8,035,255.
When the wireless type power transfer is employed, it is desired that electric power is supplied with a small energy loss from the electric power supply primary coil to the electric power supply secondary coil.
Furthermore, when the wireless type power transfer is employed to supply electric power from the electric power supply primary coil to the electric power supply secondary coil, it is desired that usage is easy.
In the wireless power transfer system, electric power is supplied in a wireless manner from the electric power supply primary coil to the electric power supply secondary coil via a magnetic field formed in a space between the electric power supply primary coil and the electric power supply secondary coil.
This feature imposes a reasonable restriction on a distance and a misalignment between the electric power supply primary coil and the electric power supply secondary coil. An attempt to supply electric power while exceeding the restriction of distance and misalignment leads to failure, that is, a large energy loss.
In a case where the electric power supply secondary coil is incorporated in a vehicle, a position of the electric power supply secondary coil is different depending on a vehicle type. In a case where wireless power transfer with a small energy loss is expected, positioning of the electric power supply secondary coil and the electric power supply primary coil is required.